1. Field of the Invention
The present invention generally relates to a system for controlling battery conditions.
2. Description of Related Art
Often network access devices, such as those associated with vehicle telematics systems, will need to operate in emergency situations. This functionality may be necessary whether or not the vehicle power systems are functioning or even connected. Accordingly, back up batteries are typically provided for these network access devices.
However, the effectiveness of a battery to supply sufficient power is diminished when the temperature of the battery is close to or below 0° C. The lower temperature increases the output impedance of the battery causing increased voltage drop between the cell and the load when the load current increases. Depending on the battery chemistry, this effect may be more pronounced.
The effect of this increased impedance is to reduce the available talk time as the ambient temperature is decreased. For ECALL applications, customers are expecting the ability to maintain a call for up to 11 minutes at −20° C. or 5 minutes at −30° C.